LeetCode, leetcodeoj

LeetCode, leetcodeoj

Question:

Given two binary strings, return their sum (also a binary string ).

For example,
A ="11"
B ="1"
Return"100".

Ideas:

Recursion. Note that the recursion termination condition is I <0 & j <0 & carray <1

package manipulation;public class AddBinary {    public String addBinary(String a, String b) {        int alen = a.length();        int blen = b.length();        StringBuilder sb = new StringBuilder();        add(alen - 1, blen - 1, 0, a, b, sb);        return sb.toString();    }        private void add(int i, int j, int carry, String a, String b, StringBuilder sb) {        if (i <0 && j < 0 && carry < 1) return;        int m = i >= 0 ? (a.charAt(i) - '0') : 0;        int n = j >= 0 ? (b.charAt(j) - '0') : 0;        int total = m + n + carry;        add(i - 1, j - 1, total / 2, a, b, sb);        sb.append((char)(total % 2 +'0'));    }        public static void main(String[] args) {        // TODO Auto-generated method stub        AddBinary a = new AddBinary();        System.out.println(a.addBinary("0", "0"));    }}